There is a paper feeding apparatus which automatically feeds a paper to be read, on which information composed of characters or the like is recorded, or a paper to be printed one. This kind of paper feeding apparatus is mounted on an electronic apparatus such as a facsimile machine, a scanning machine, a printing machine, a copying machine or the like. The paper feeding apparatus is one of the feeding apparatus.
This kind of paper feeding apparatus includes, for example, a circular paper feeding path, a paper introducing inlet arranged on the paper feeding path, a paper discharging path branched from the paper feeding path and extended to a paper discharging outlet, a pair of paper feeding rollers arranged on the paper feeding path and which pinches the paper and feeds the paper in a first direction (first circling direction), and a pair of paper discharging and reverse feeding rollers arranged on the paper discharging path, which pinches the paper and feeds the paper in a forward direction to the paper discharging outlet and feeds the paper in a backward direction to return the paper to the paper feeding path. Each roller, included in the pair of paper discharging and reverse feeding rollers, is arranged so as to be facing to a first surface (one of a front surface and a back surface) of paper or a second surface (the other of the front surface and the back surface) of paper respectively. The pair of paper discharging and reverse feeding rollers feeds the paper using the rollers being driven to be rotated by a driving source in the opposite direction of each other.
The paper feeding apparatus works as follows. First, the pair of paper feeding rollers feeds a paper, which is inserted from the paper introducing inlet, on the paper feeding path in the first direction while keeping a front edge of the paper as a feeding head. When the paper is fed on the paper feeding path in the first direction, information is read, for example, from the first surface of the paper by an optical head. Next, the pair of paper feeding rollers and the pair of paper discharging and reverse feeding rollers feed the paper, whose information indicated on the first surface is read, on the paper discharging path in the forward direction while keeping the front edge of the paper as the feeding head and put the paper on the paper discharging path. Afterward, the pair of paper feeding rollers and the pair of paper discharging and reverse feeding rollers feed the paper, which is put on the paper discharging path, on the paper discharging path in the backward direction while keeping a rear edge of the paper as the feeding head, and furthermore, feed the paper on the paper feeding path in the first direction. When the paper is fed on the paper feeding path in the first direction, information is read from the second surface of the paper by an optical head. Next, the pair of paper feeding rollers and the pair of paper discharging and reverse feeding rollers feed the paper, whose information indicated on the front surface and the back surface is read, on the paper feeding path in the first direction while keeping the rear edge of the paper as the feeding head and feed the paper on the paper discharging path in the forward direction and then, discharge the paper from the paper discharging outlet.
According to the paper feeding apparatus mentioned above, a rear edge of a paper which is fed on the paper discharging path in the backward direction in order to be returned to the paper feeding path, and a front edge of another paper which is fed on the paper discharging path in the forward direction in order to be discharged from the paper discharging outlet are rubbed together at between the paper discharging and reverse feeding rollers. At this time, the front edge of another paper, which is fed in the forward direction, may be deformed in some cases. As a result, another paper fails in being introduced into a space between the paper discharging and reverse feeding rollers and then, the paper is bent and torn.
As a measure to cope with the above-mentioned defect, there is a paper feeding apparatus which can prevent from both of papers being rubbed together. The paper feeding apparatus has the pair of paper discharging and reverse feeding rollers, which of each roller being moved away from the other roller, when two papers pass each other.
With reference to FIG. 1, the paper feeding apparatus, which applies the measure, includes a pair of paper discharging and reverse feeding rollers 150, composed of a first paper discharging and reverse feeding roller 151 and a second paper discharging and reverse feeding roller 152 which of the roller is facing each other through a paper, arranged on a paper discharging path 14, an un-illustrated sensor to detect that a front edge of the paper reaches to the pair of paper discharging and reverse feeding rollers 150, and a solenoid 185 which drives the second paper discharging and reverse feeding roller 152 to move the second paper discharging and reverse feeding roller 152 away from the first paper discharging and reverse feeding roller 151 based on a detection signal generated by the sensor. Further, symbols 20 and 30 indicate respectively pairs of paper feeding rollers which are arranged on a paper feeding path 10 composed of sections 11 and 12. Symbol 40 indicates a pair of paper introducing rollers which is arranged on a paper introducing path 13 for introducing a paper into the paper feeding path 10.
Further, a kind of paper feeding apparatus, which can turn a paper inside out automatically, is disclosed, for example, in Japanese Patent Application Laid-Open No. 2005-335915 (hereinafter, patent document 1), Japanese Patent Application Laid-Open No. 2006-103946 (hereinafter, patent document 2), Japanese Patent Application Laid-Open No. 1993-310356 (hereinafter, patent document 3) and Japanese Patent Application Laid-Open No. 1997-86807 (hereinafter, patent document 4).
A paper feeding apparatus disclosed in the patent document 1 includes a paper discharging and reverse feeding roller which is connected to a driving source, and a pinch roller which is facing to the paper discharging and reverse feeding roller through a paper and which is a slave roller for the paper discharging and reverse feeding roller. The paper discharging and reverse feeding roller is arranged on the upper side and the pinch roller is arranged on the lower side, and the paper discharging and reverse feeding roller is constituted so as to be shifted in an upper direction. According to the above mentioned structure, it can prevents a paper which has been just discharged, from returning accidentally to the paper feeding path together with another paper which is fed in the backward direction.
A paper feeding apparatus disclosed in the patent document 2 includes a pair of paper discharging and reverse feeding rollers which are facing each other through a paper, a sensor to detect that a front edge of a paper reaches near to the pair of paper discharging and reverse feeding rollers, and a combination of a stepping motor and a lever mechanism which drives one paper discharging and reverse feeding roller on the basis of a detection signal generated by the sensor so that the one paper discharging and reverse feeding roller may be moved away from the other paper discharging and reverse feeding roller.
A paper feeding apparatus disclosed in the patent document 3 includes a tri-roll apparatus which is arranged at a boundary area of a paper feeding path and a paper discharging path, and a driving roller and a pinch roller which are facing each other through a paper. Pressing force of the pinch roller is set quite weak. In the case that two papers are introduced between the driving roller and the pinch roller, the pinch roller moves away from the driving roller.
A paper feeding apparatus disclosed in the patent document 4 includes a driving roller and a slave roller which are facing each other through a paper, and a solenoid which drives the slave roller so that the slave roller may be moved away from the driving roller in the case that two papers are introduced between the driving roller and the pinch roller.